1195-92-2Relevant articles and documents
Highly selective and recyclable MoO3 nanoparticles in epoxidation catalysis
Fernandes, Cristina I.,Capelli, Silvia C.,Vaz, Pedro D.,Nunes, Carla D.
, p. 344 - 350 (2015)
Molybdenum trioxide (MoO3) nanoparticles with an average size below 100 nm were prepared by solvothermal synthesis of nano-crystalline molybdenum dioxide (MoO2) and subsequent thermal oxidative annealing. The successful preparation of this type of nanoparticles was confirmed by evidence obtained from characterization by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis and Fourier transform infrared spectroscopy (FTIR). The MoO3 nanoparticles were tested as catalytic precursor in the epoxidation of cis-cyclooctene, styrene, R-(+)-limonene and trans-hex-2-en-1-ol, using tert-butylhydroperoxide (tbhp) as oxygen source under different reaction conditions, namely, various solvents and temperatures. The catalytic studies show that the MoO3 nanoparticles perform selective epoxidation of the tested substrates with very high yield, especially at high temperature and using toluene as solvent. Furthermore, the catalyst remains active across several reaction cycles with virtually no loss of activity.
Monovacant polyoxometalates incorporated into MIL-101(Cr): Novel heterogeneous catalysts for liquid phase oxidation
Granadeiro, Carlos M.,Barbosa, André D.S.,Silva, Patrícia,Paz, Filipe A. Almeida,Saini, Vipin K.,Pires, Jo?o,De Castro, Baltazar,Balula, Salete S.,Cunha-Silva, Luís
, p. 316 - 326 (2013)
Two novel hybrid composite materials, PW11@MIL-101 and SiW 11@MIL-101, were prepared by the inclusion of the potassium salts of the monovacant polyoxotungstates, [PW11O39]7- (PW11) and [SiW11O39]8- (SiW 11), into the porous Metal-Organic Framework MIL-101(Cr). Materials were characterized by a myriad of solid-state methods such as powder X-ray diffraction (XRD), vibrational (FT-IR and FT-Raman) and 31P solid-state NMR spectroscopies, elemental analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), and textural analysis confirming the incorporation of the POMs into MIL-101(Cr). PW 11@MIL-101 and SiW11@MIL-101 revealed to be active, selective and recyclable catalysts for the oxidation of cis-cyclooctene, geraniol and R-(+)-limonene using the H2O2 as oxidant. Only one product was obtained from the epoxidation of cis-cyclooctene and geraniol: 1,2-epoxycylooctane and 2,3-epoxygeraniol, respectively. In the oxidation of R-(+)-limonene the main products were limonene-1,2-epoxide and limonene-1,2-diol, however the diepoxide was also formed. Both composite materials, PW11@MIL-101 and SiW11@MIL-101, are recyclable for, at least, three consecutive cycles without significant loss of activity. The stability of the composites after the catalytic cycles was confirmed by several techniques. Remarkably, the MOF framework was found to play an important role in the stability of the PW11 in the presence of H 2O2.
Hydrogen-peroxide epoxidation of natural olefins catalyzed by a dinuclear manganese complex
Mandelli,Voitiski,Schuchardt,Shul'pin
, p. 243 - 245 (2002)
The complex of Mn(IV) with the macrocyclic N-containing ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (L) [L2Mn2O 3](PF6)2 catalyzes epoxidation of (+)-limonene in CH3CN solution at room temperature. Adding CH3COOH accelerates the reaction. The products are isomers of limonene epoxide with predominance of that with an epoxified ring double bond. Epoxidation of α- and β-pinene by this system is less effective, apparently due to extensive steric shielding of the double bonds in the pinenes.
[Mn(TPPS)] immobilized on ionic liquid-modified silica as a heterogeneous and reusable catalyst for epoxidation of alkenes with NaIO4 under ultrasonic irradiation
Hajian, Robabeh,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
, p. 1061 - 1067 (2016)
Effective epoxidation of alkenes using sodium periodate was accomplished with Manganese (III) tetrakis(p-sulfonatophenyl)porphyrin, [C44H26N4O12S4Na4], supported on ionic liquids-modified silica, Im-SiO2, under ultrasonic irradiation conditions is reported. This heterogeneous catalyst, [Mn(TPPS)@SiO2-Im] was characterized by elemental analysis, scanning electron microscopy (SEM), FT-IR and UV–Vis spectroscopic methods. The synthesized hybrid catalyst was applied for efficient epoxidation of various alkenes with sodium periodate in acetonitrile under ultrasonic irradiation conditions. This solid catalyst can be easily recovered by simple filtration and reused several time without apparent loss of its catalytic activity.
Fluorinated alcohols: Effective solvents for uncatalysed epoxidations with aqueous hydrogen peroxide
Van Vliet,Arends,Sheldon
, p. 248 - 250 (2001)
Buffered aqueous hydrogen peroxide in combination with fluorinated alcohols (trifluoroethanol at reflux temperature or hexafluoro-2-propanol at room temperature) oxidises a variety of alkenes to the corresponding epoxides in high rates and fairly high yields, without the need for any catalyst.
Eco-friendly solvents and amphiphilic catalytic polyoxometalate nanoparticles: A winning combination for olefin epoxidation
Mouret, Adrien,Leclercq, Loic,Muehlbauer, Andrea,Nardello-Rataj, Veronique
, p. 269 - 278 (2014)
Eighteen eco-friendly solvents were examined to carry out the epoxidation of olefins with the amphiphilic catalytic dodecyltrimethylammonium polyoxometalate nanoparticles [C12]3[PW12O 40] in comparison with [H]3[PW12O40] and [Na]3[PW12O40]. Surprisingly, the screening of solvents with cyclooctene has revealed that the [C 12]3[PW12O40] catalyst is much more active with initial turn-over frequencies, TOF0, increasing up to a factor of 10. Moreover, the reaction occurs at competitive rates in four relevant solvents, i.e. cyclopentyl methyl ether, 2-methyl tetrahydrofuran, methyl acetate and glycerol triacetate, for which TOF0 values are higher than 260 h-1. The recyclability of the systems is demonstrated and the scope of substrates has been successfully extended to cyclohexene, 1-octene, limonene, 3-carene, α-pinene, β-pinene and neryl acetate with good epoxide selectivity. The catalytic performances in the "green" solvent are assigned to the formation of stable [C 12]3[PW12O40] nanoparticle dispersions which have been characterized by transmission electron microscopy and dynamic and multiple light scattering experiments. Finally, the Kamlet-Taft parameters were measured in order to correlate the physicochemical properties of the solvents and the catalytic activity.
Vanadyl cationic complexes as catalysts in olefin oxidation
Nunes, Carla D.,Vaz, Pedro D.,Félix, Vítor,Veiros, Luis F.,Moniz, Tania,Rangel, Maria,Realista, Sara,Mourato, Ana C.,Calhorda, Maria José
, p. 5125 - 5138 (2015)
Three new mononuclear oxovanadium(iv) complexes [VO(acac)(R-BIAN)]Cl (BIAN = 1,2-bis{(R-phenyl)imino}acenaphthene, R = H, 1; CH3, 2; Cl, 3) were prepared and characterized. They promoted the catalytic oxidation of olefins such as cyclohexene, cis-cyclooctene, and styrene with both tbhp (tert-butylhydroperoxide) and H2O2, and of enantiopure olefins (S(-)- and R(+)-pinene, and S(-)- and R(+)-limonene) selectively to their epoxides, with tbhp as the oxidant. The TOFs for styrene epoxidation promoted by complex 3 with H2O2 (290 mol mol-1V h-1) and for cis-cyclooctene epoxidation by 2 with tbhp (248 mol mol-1V h-1) are particularly good. Conversions reached 90% for several systems with tbhp, and were lower with H2O2. A preference for the internal CC bond, rather than the terminal one, was found for limonene. Kinetic data indicate an associative process as the first step of the reaction and complex [VO(acac)(H-BIAN)]+ (1+) was isolated in an FTICR cell after adding tbhp to 1. EPR studies provide evidence for the presence of a V(iv) species in solution, until at least 48 hours after the addition of tbhp and cis-cyclooctene, and cyclic voltammetry studies revealed an oxidation potential above 1 V for complex 1. DFT calculations suggest that a [VO(H-BIAN)(MeOO)]+ complex is the likely active V(iv) species in the catalytic cycle from which two competitive mechanisms for the reaction proceed, an outer sphere path with an external attack of the olefin at the coordinated peroxide, and an inner sphere mechanism starting with a complex with the olefin coordinated to vanadium. This journal is
Perfluoroheptadecan-9-one: A selective and reusable catalyst for epoxidations with hydrogen peroxide
Van Vliet, Michiel C. A.,Arends, Isabel W. C. E.,Sheldon, Roger A.
, p. 263 - 264 (1999)
Perfluoroheptadecan-9-one is a selective and mild catalyst for the epoxidation of a wide variety of alkenes with hydrogen peroxide; after the reaction the catalyst can be easily recovered and reused without noticable decomposition.
Continuous flow photooxygenation of monoterpenes
Park, Chan Yi,Kim, Young Joon,Lim, Hyo Jin,Park, Jeong Hyeon,Kim, Mi Jin,Seo, Seung Woo,Park, Chan Pil
, p. 4233 - 4237 (2015)
Photooxygenation of monoterpenes was conducted in two continuous flow reactors. The first, suitable for lab-scale research, had a maximum yield of 99.9%, and the second, focused on industrial applications, showed a daily output that was 270.0-fold higher than that in batch systems. The use of sunlight instead of an LED lamp gave 68.28% conversion.
Titanosilsesquioxane anchored on mesoporous silicas: A novel approach for the preparation of heterogeneous catalysts for selective oxidations
Carniato, Fabio,Bisio, Chiara,Boccaleri, Enrico,Guidotti, Matteo,Gavrilova, Elena,Marchese, Leonardo
, p. 8098 - 8101 (2008)
Ti-polyhedral oligomeric silsesquioxanes (Ti-POSS) based heterogeneous catalysts were prepared by anchoring of a functional titanium-containing silsesquioxane on the surface of an ordered mesoporous silica (SBA-15) and a non-ordered silica (SiO2-Dav). The anchoring process was followed by IR spectroscopy, which leads to the condensation reactions between surface silanols of silicas and ethoxy groups. The heterogeneous character of catalysts checked by removing the solid catalyst by centrifugation and testing the residual liquid mixture show no significant loss of active species. Anchored heterogeneous catalysts show lower conversions with respect to reference materials prepared by direct grafting of titanocene on the same silica supports. It is also seen that the anchored materials display slightly better results than those obtained over reference titanium-silica catalysts with comparable metal loading.
